Struggling battery-car start-up Fisker Automotive is hoping some star power can charge up its sales and image and will get that helping hand from green-minded Leonardo DiCaprio.

The silver screen celebrity has long been an active proponent of clean machines like the Toyota Prius, notably driving one of the first of those hybrids to the Academy Awards a decade ago. He now owns one of the $102,000 Fisker Karma plug-ins – and has invested in the California-based firm.

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But DiCaprio plans to go a step further, using his star power to promote the Fisker brand as part of a campaign for global sustainability.

“My foundation supports efforts to secure a sustainable future for our planet and all its inhabitants,” says DiCaprio. “I am delighted to be working with Fisker Automotive to promote this shared vision.”

While sales of the Karma got off to a slow – and late – start, the sleek sports car has generated plenty of buzz in celebrity circles. Former Secretary of State Colin Powell was one of the earlier customers. But DiCaprio received the first production-ready Fisker Karma to roll off the line.

Developed by Henrik Fisker, one-time styling chief of Aston Martin, the Karma is a four-seat plug-in hybrid which uses a pair of electric motors to drive its wheels. Together they produce up to 400 horsepower and can launch from 0 to 60 in as little as 6.1 seconds, with a top speed of 125 mph.

The Karma is also outfitted with a 2.0-liter four-cylinder engine provided by General Motors that serves as a back-up generator once the sports car’s lithium-ion battery pack is depleted. The car is rated at 32 miles range on batteries alone, according to the EPA, with a 32 MPGe rating. But European tests have come up with a more generous 51 miles range and a whopping 112 MPGe rating.

Fisker Automotive has faced a number of problems in recent months, starting with the late launch of the Karma – one reason the Dept. of Energy froze a $529 million loan. The carmaker has been scrambling to raise additional money needed to complete the development and launch of its second product, the smaller and lower-cost Atlantic. Debut of that model has now been delayed until at least 2014.

Complicating matters, production defects at a plant run by battery supplier A123 forced the recall of many early Karma models – and the maker is now under investigation by federal safety regulators due to a suspicious fire in a Texas garage that destroyed a Karma and several other luxury vehicles. Local investigators initially pointed to the Fisker as the cause but the maker disputed that, noting that the car’s battery pack remained intact despite the fire.

Fisker officials are hoping DiCaprio’s presence will give their struggling brand some credibility – and not bring the company down like the ship he sailed on in the film that gave DiCaprio his first big star turn, “Titanic.”